The present invention relates to wobble dado cutting circular saw arrangements and more particularly to a dual blade dado cutting arrangement wherein at least one point on the periphery of each of the blades is maintained juxtapositioned.
In some present dado cutting arrangements, a single blade is employed for cutting dados of varying widths. When a single blade is employed for cutting dados of varying thickness, the blade is pivoted on the axis of the spindle. In this type arrangement, the single blade pivots or wobbles about the axis as it cuts the full width of the dado. This pivoting or wobbling action of the blade in traversing the full width of the dado cuases its peripheral edge to travel through a plane which is not parallel with the axis of rotation. The arc through which the peripheral edge of the blade travels causes the bottom or base wall of the dado to be curved. Further, the torque force of the wobbling blade causes an unbalance of forces that results in both rotational and torsional vibrations. In some instances, depending on the obliquity of the blade and speed of rotation, the vibration can be objectionable. In U.S. Pat. No. 17,823 (Harrison), two saw blades are employed with each blade being independently adjustable. In this instance, the blades are spaced apart with each blade pivoted about the spindle so as to leave a tongue of a desired thickness between the blades. This arrangement merely employs two separate one blade systems to cut away an area on either side of a tongue. The blades in this arrangement, which are pivoted about the axis of rotation, may in fact increase the torque forces depending on the position of the blades relative to each other.
Accordingly, it is an object of the present invention to provide a twoblade dado cutting arrangement wherein the vibration caused by the rotation of the wobbling blades is minimized by positioning the blades so that the forces generated by each blade neutralize each other.